president obama was in miami, at a spanish language town hall sponsored by univision and facebook. there, he was asked about his failure to keep a 2008 pledge of comprehensive immigration reform within his first year. >> and a promise is a promise. and with all due respect, you didn't keep that promise. >> well, here's what i would say, jorge, is that-- and we've had this conversation before. there's the thinking that the president is somebody who is all-powerful and can get everything done. in our branch of-- in our system of government, i am the head of the executive branch. i'm not the head of the legislature. i'm not the head of the judiciary. we have to have cooperation from all these sources in order to get something done. and so i am happy to take responsibility for the fact that we didn't get it done, but i did not make a promise that i would get everything done 100% when i was elected as president. >> woodruff: claiming congressional republicans walked away from an immigration overhaul, mr. obama used his administration's support of the "dream act" -- to aid immigrants bro